CN1050643C - Oxygen bleaching method of daily producing 30-50 tons medium density paper pulp - Google Patents
Oxygen bleaching method of daily producing 30-50 tons medium density paper pulp Download PDFInfo
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- CN1050643C CN1050643C CN 96119117 CN96119117A CN1050643C CN 1050643 C CN1050643 C CN 1050643C CN 96119117 CN96119117 CN 96119117 CN 96119117 A CN96119117 A CN 96119117A CN 1050643 C CN1050643 C CN 1050643C
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Abstract
The present invention relates to a hydrogen peroxide bleaching method for producing 30 to 50 tons of medium concentration paper pulp each day. 2 to 5% of alkaline liquor, 0.1 to 0.2% of magnesium salt and 1.5 to 2.5% of oxygen measured by absolute dry pulp weight are added into paper pulp with the concentration of 9 to 14 wt% and fully mixed through a medium concentration pulp pump and a medium concentration mixer. The paper pulp is bleached by an upward flow bleaching pipe and a downward flow bleaching tower for 50 to 80 minutes, the temperature in the downward flow bleaching tower is from 90 to 120 DEG C, and the pressure is from 0.4 to 0.7MPa; the paper pulp is diluted to the concentration of 4 to 6 wt% at the bottom of the tower and washed to obtain bleached pulp. The present invention makes the whiteness of the paper pulp increased by 20%GE to 25%GE; exhausted waste water conforms to Chinese standards and does not pollute the environment.
Description
The present invention relates to the dioxde pulp bleaching process of pulp and paper industry.Relate to the oxygen bleaching method of careless class paper pulp in more detail.
China existing daily output 30-150 ton grass class association with pulp bleaching mainly is to utilize chlorination bleaching and hypochlorite bleaching method, and the discharge wastewater toxicity of this method is very big, and wastewater flow rate is many, thereby makes pulp and paper industry have three big problems:
(1) serious environment pollution makes pulp and paper industry become one of three the most serious big industries of China's environmental pollution;
(2) severe contamination pulping and papermaking equipments, thus equipment and materials is proposed too high requirement, decrease ring otherwise will speed up ageing equipment;
(3) have a strong impact on the healthy of operator.
In the external prior art oxygen bleaching of pulp method is arranged also, but this method only is applicable to wood type paper pulp, is not suitable for careless class paper pulp.This is that fibre strength is lower, and careless class paper pulp the ash content of coal height because grass fiber is shorter than wood pulp fibre.So the oxygen bleaching method of wood pulp can not be applicable to the oxygen bleaching method of straw pulp fully.
The objective of the invention is to overcome the deficiencies in the prior art part, a kind of method for bleaching of middle concentration paper pulp is provided, and the oxygen bleaching method of dense careless class paper pulp in especially being suitable for makes discharge waste water reach environmental requirement, pollution-free to pulping and papermaking equipments, do not influence the healthy of workman.
Because the production scale of China's paper pulp is daily output 30-150 ton oven dry stock mostly, so the present invention studies the middle concentration paper pulp method for bleaching of 30 ton per days, 50 ton per days, 100 ton per days, 150 ton per day scales emphatically.
The middle concentration paper pulp oxygen bleaching method of daily output 30-150 ton oven dry stock of the present invention comprises the steps:
(1) washing concentrating
The low-consistency stock of 3～6% weight, by being pumped into wash engine, the pulp density after washing concentrating is brought up to 9～14% weight, falls in the defeated material spiral that is installed on the wash engine bottom;
(2) add alkali lye bleaching assistant and magnesium salt protective agent
Will be by oven dry stock weight, consumption is that 2～5% alkali lye and consumption are that 0.1～0.2% magnesium salts adds in the defeated material spiral, be transported to mixing screw with paper pulp, feeding steam pressure in mixing the process of carrying is that 0.5～0.8MPa, temperature are 150～180 ℃ low-pressure steam, make temperature of charge reach 90～120 ℃, concentration remains in 8～13% weight ranges, be admitted to the storage slurry standpipe of middle underflow pump, dense blender in middle underflow pump is sent into, the outlet pressure of middle underflow pump are 0.6～0.9MPa;
(3) paper pulp and oxygen mix
Therefrom the oxygen intake of dense blender feeds the oxygen of pressure a little more than the middle underflow pump outlet pressure, bleaching agent oxygen use amount counts 1.5～2.5% by oven dry stock weight, in fully mix with paper pulp in the dense blender, mixture homogeneity reaches 95%, enter up-flow bleaching pipe then, this moment, the paper pulp temperature still remained in 90～120 ℃ of scopes;
(4) bleaching
Paper pulp behind the control pressure regulating valve, directly be admitted to by up-flow bleaching pipe and fall the stream bleaching tower, the bleaching tower temperature is 90-120 ℃, pressure is 0.4～0.7MPa, the material stop reaction time is 50～80min in bleaching tower, at the bottom of tower, paper pulp is diluted to 4～6% weight, pumps to another wash engine, after washing, get bleached pulp by low-consistency.
Alkali lye bleaching assistant used in the present invention is a NaOH, and magnesium salt protective agent can be magnesium silicate, magnesium carbonate, magnesium sulfate, magnesia, magnesium hydroxide.
The paper pulp that the present invention uses can be careless class chemical method paper pulp, and the present invention also can be used for the bleaching of wooden class chemical method paper pulp.
In concentrated oxygen bleaching and high dense hydrogen peroxide bleaching can divide multistage to be connected into whole bleaching system, can obtain being applicable to that cultural paper, paper for daily use, industrial or agricultural are with needed whiteness such as paper.
Equipment used in the present invention can be commercially available, also can self design.
The present invention compared with prior art has following advantage:
(1) the whiteness increment 20%GE-25%GE of paper pulp before the paper pulp contrast of adopting this law to produce is not bleached.
(2) waste water that the association with pulp bleaching of paper industry is discharged meets state specified standards, and environment is not brought pollution.
(3) equipment in association with pulp bleaching workshop and the equipment of downstream process workshop section are not produced any pollution, so just prolonged the service life of equipment, reduced the running cost of pulping and paper-making factory.
(4) make the discharge waste water environmental pollution degree of pulping and paper-making factory reduce half, make pulp and paper industry stride forward major step to clean industry.
(5), thereby operator's healthy nothing is influenced because bleaching agent and protective agent are nontoxic, and bleaching effluent is also nontoxic.
(6) owing to operating system automation and serialization degree height, thereby make association with pulp bleaching quality height, more can not damage quality of fibre in the paper pulp.
Below by embodiment the present invention is further described below.
Embodiment 1
Produce 30 tons wheat straw chemical method middle concentration paper pulp oxygen bleaching method daily, its step and process conditions are as follows:
(1) washing concentrating:
With stock pump the low-consistency stock of 3wt%, whiteness 35%GE is sent into wash engine, the pulp density after washing concentrating is brought up to 10wt%, and 30 ℃ of temperature are fallen into the defeated material spiral of wash engine bottom;
(2) add alkali lye bleaching assistant and magnesium salt protective agent:
The NaOH that in defeated material spiral, adds 2% (in oven dry stock weight), and the Adlerika of adding 0.1% (in oven dry stock weight), and send into mixing screw with paper pulp, in mixing the process of carrying, feed pressure 0.5MP, the low-pressure steam that temperature is 150 ℃, make temperature of charge reach 90 ℃, paper pulp is admitted to the storage slurry standpipe of middle underflow pump then, and the steam heat of input mixing screw is 8.5 * 10
5(kilocalorie/hour), this moment, pulp density reduced to 9%;
(3) paper pulp and oxygen mix:
Paper pulp is dense blender during the middle underflow pump of 0.6MPa enters through outlet pressure, in import oxygen simultaneously in the dense blender, oxygen is pressed and is 0.7MPa, input quantity is 1.5% (in oven dry stock weight), oxygen and paper pulp mixture homogeneity are 95%;
(4) bleaching:
Enter up-flow bleaching pipe after paper pulp and the oxygen mix, temperature keeps 90 ℃, the high 13m of up-flow bleaching pipe, and diameter 400mm, the top is provided with control valve, can regulate paper pulp and enter the pressure that falls the stream bleaching tower.After paper pulp entered bleaching tower, the time of staying was 60min, and the tower internal pressure is 0.4MPa, 90 ℃ of temperature, and the bleaching tower lower end is provided with the dilution runner, can be the paper pulp dilution 4% weight, pumps wash engine by general stock pump.The flowing time of paper pulp at the bottom of from the bleaching tower top to tower is exactly the reaction time, is 60min.Therefore, the definite of the height of tower and diameter must satisfy association with pulp bleaching stop reaction time and permissible velocity of flow value, and present embodiment is tower height 13m, and diameter is 1.3m, and paper pulp just becomes bleached pulp after washing, and whiteness reaches 55%GE.BOD in the waste water is discharged in the bleaching back
5Be 100mg/L, COD
CTBe 300mg/L, be lower than national grade ii standard.
The capital equipment that present embodiment is selected for use is as follows:
Two wash engines that step 1 and 4 is used all adopt model to be ZNK
4Vacuum pulp washing machine, Anyang machinery plant of the light machine parent company of China product; Defeated material screw machine is that SPP30 and mixing screw model are SMP30, is Fujian Machinery Plant of Light Industry and makes; Turbulence type middle underflow pump ZBJ31-30, the light machine in Tianjin factory makes; In dense blender be the AHLMIX-30 type, Finland Ahlstrom Co. makes; Up-flow bleaching pipe and model are that the bleaching tower of MPB-30 is made by Fujian Machinery Plant of Light Industry.
Embodiment 2
Produce 150 tons of chemical method sulphite pine middle concentration paper pulp oxygen bleaching methods daily.
(1) washing concentrating:
The low dense sulphite pine slurry of 6wt% is by being pumped into wash engine, and the pulp density after washing concentrating reaches 14wt%, 30 ℃ of temperature, and whiteness 35%GE falls into the defeated material spiral of rinsing maching bottom;
(2) add alkali lye bleaching assistant and magnesium salt protective agent:
The magnesium silicate solution that adds the NaOH and 0.2% (in absolute dried paper pulp weight) of 5% (in absolute dried paper pulp weight), send into mixing screw with paper pulp, and in mixing screw, feed pressure 0.8MPa, the low-pressure steam that temperature is 180 ℃, make temperature of charge reach 120 ℃, the vapour heat that adds mixing screw is 41.5 * 10
5(kilocalorie/hour);
(3) paper pulp and oxygen mix:
Paper pulp is dense blender during the middle underflow pump of 0.9MPa enters through outlet pressure, aerating oxygen pressure is 1.0MPa simultaneously, input quantity is 2.5% (in oven dry stock weight), oxygen mixes with paper pulp, its mixture homogeneity is 95%, also keeps 120 ℃ paper pulp to be admitted to up-flow bleaching pipe with temperature after the oxygen mix;
(4) bleaching:
The high 17m of up-flow bleaching pipe, diameter 600mm, the top is provided with control valve, can regulate paper pulp and enter the pressure that falls the stream bleaching tower, enter through the paper pulp of control valve and fall the stream bleaching tower, the temperature of falling in the stream bleaching tower is 120 ℃, pressure 0.7MPa, concentration still keeps 13% weight, and the time of paper pulp from overhead streams to the dilution zone, bottom is exactly bleaching time, i.e. 78min.The bleaching tower height of present embodiment is 18.5m, and diameter is 2m.Paper pulp is diluted as 6% weight concentration at the bottom of tower, pump to wash engine by low-consistency and wash.Paper pulp contrast after the washing not whiteness increment of the preceding paper pulp of bleaching is 25%GE, and whiteness reaches 60%GE, BoD in the bleaching back discharge waste water
5Be 100mg/L, CoD
CTBe 300mg/L, be lower than national grade ii standard.
The capital equipment that present embodiment is selected for use is as follows:
Two rinsing maching models that step 1 and 4 is used are the ZNK10 vacuum pulp washing machine, and Anyang Machinery Plant of Light Industry makes; Conveyor screw machine SPP150 and mixing screw model are SMP150, are Fujian light machine factory and make; Turbulence type middle underflow pump model is ZBJ31-150, and the light machine in Tianjin factory makes; In dense mixer model be AHLMIX-150, Finland Ahlstrom Co. makes; Up-flow bleaching pipe is made by the light machine in Fujian factory: the bleaching tower model is MPB150, and the light machine in Fujian factory makes.
Embodiment 3
Produce concentration Eucalyptus oxygen bleaching of pulp method in 100 tons of chemical methods daily
(1) washing concentrating:
The low dense chemical method Eucalyptus paper pulp of 4wt% is by being pumped into wash engine, and the pulp density after washing concentrating reaches 13wt%, 32 ℃ of temperature, and whiteness 34%GE falls into the defeated material spiral of wash engine bottom;
(2) add alkali lye and magnesium salts:
The magnesium carbonate solution that in defeated material spiral, adds the NaOH and 0.15% (in oven dry stock weight) of 3.5% (in absolute dried paper pulp weight), send in the mixing screw with paper pulp, feeding pressure in mixing screw is 0.7MPa, temperature is 170 ℃ a low-pressure steam, and temperature of charge reaches 110 ℃ after mixing.The heat that adds mixing screw is 27 * 10
5(kilocalorie/hour), this moment, pulp density was reduced to 12wt%;
(3) paper pulp and oxygen mix:
Send into the storage of middle underflow pump with the mixed paper pulp of bleaching assistant and starch standpipe, and dense blender in being pumped to by middle underflow pump, the middle underflow pump outlet pressure is 0.8MPa, the oxygen pressure of dense blender is 0.9MPa in the feeding, input quantity is 2% (in oven dry stock weight), the mixture homogeneity of oxygen and paper pulp is 95%, also keeps 110 ℃ paper pulp to be admitted to up-flow bleaching pipe with temperature after the oxygen mix;
(4) bleaching:
The high 16m of up-flow bleaching pipe, diameter 500mm, the control valve that is located at the top can be regulated control paper pulp and enter the pressure that falls the stream bleaching tower, paper pulp enters from the upspout top and falls the stream bleaching tower, falling the interior temperature of stream bleaching tower is 110 ℃, and pressure 0.6MPa, pulp density still keep 12%, bleaching time is 70min, tower height 16m, diameter are 1.8m, and paper pulp is diluted as 5% weight concentration at the bottom of tower, pump to another wash engine by low-consistency and wash, just become bleached pulp.
The washing back paper pulp contrast not preceding pulp brightness increment of bleaching is 23%GE, reaches 57%GE.Bleaching process is discharged BoD in the waste water
5Be 100mg/L, CoD
CTBe 280mg/L, be lower than national grade ii standard.
The capital equipment that present embodiment is selected for use is:
Step 1 and 4 two suction washer ZNKZ that use
10, Anyang Machinery Plant of Light Industry makes; Conveyor screw machine SPP100 and mixing screw SMP100 are Fujian light machine factory and make; Turbulence type middle underflow pump model is that ZBJ31-100 Tianjin light machine factory makes; In dense blender AHLMIX-100, Finland Ahlstrom Co. makes; Up-flow bleaching pipe is made by the light machine in Fujian factory; The bleaching tower model is MPB-100, and the light machine in Fujian factory makes.
Claims (2)
1, the middle concentration paper pulp oxygen bleaching method of daily output 30-150 ton oven dry stock is characterized in that comprising the steps:
(1) washing concentrating
The low-consistency stock of 3～6% weight, by being pumped into wash engine, the pulp density after washing concentrating is brought up to 9～14% weight, falls in the defeated material spiral that is installed on the rinsing maching bottom;
(2) add alkali lye bleaching assistant and magnesium salt protective agent
Will be by oven dry stock weight, consumption is that 2～5% alkali lye and consumption are that 0.1～0.2% magnesium salts adds in the defeated material spiral, be transported to mixing screw with paper pulp, feeding steam pressure in mixing the process of carrying is that 0.5～0.8MPa, temperature are 150～180 ℃ low-pressure steam, make temperature of charge reach 90～120 ℃, concentration remains in 8～13% weight ranges, be admitted to the storage slurry standpipe of middle underflow pump, dense blender in middle underflow pump is sent into, the outlet pressure of middle underflow pump are 0.6～0.9MPa;
(3) paper pulp and oxygen mix
Therefrom the oxygen intake of dense blender feeds the oxygen of pressure a little more than the middle underflow pump outlet pressure, bleaching agent oxygen use amount counts 1.5～2.5% by oven dry stock weight, in fully mix with paper pulp in the dense blender, mixture homogeneity reaches 95%, enter up-flow bleaching pipe then, this moment, the paper pulp temperature still remained in 90～120 ℃ of scopes;
(4) bleaching
Paper pulp behind the control pressure regulating valve, directly be admitted to by up-flow bleaching pipe and fall the stream bleaching tower, the bleaching tower temperature is 90～120 ℃, pressure is 0.4～0.7MPa, the material stop reaction time is 50～80min in bleaching tower, at the bottom of tower, paper pulp is diluted to 4～6% weight, pumps to another rinsing maching, after washing, get bleached pulp by low-consistency.
2, concentration oxygen bleaching of pulp method in 30～150 tons of the daily outputs according to claim 1 is characterized in that alkali lye used in the present invention is NaOH, and magnesium salt protective agent can be magnesium silicate, magnesium carbonate, magnesium sulfate, magnesia, magnesium hydroxide.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 96119117 CN1050643C (en) | 1996-07-25 | 1996-07-25 | Oxygen bleaching method of daily producing 30-50 tons medium density paper pulp |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 96119117 CN1050643C (en) | 1996-07-25 | 1996-07-25 | Oxygen bleaching method of daily producing 30-50 tons medium density paper pulp |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1151460A CN1151460A (en) | 1997-06-11 |
| CN1050643C true CN1050643C (en) | 2000-03-22 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 96119117 Expired - Fee Related CN1050643C (en) | 1996-07-25 | 1996-07-25 | Oxygen bleaching method of daily producing 30-50 tons medium density paper pulp |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100400744C (en) * | 2006-05-26 | 2008-07-09 | 华南理工大学 | Moderate-thick paper pulp pressure stabilizing dual flow-lift tower oxygen bleaching method |
| CN102212979B (en) * | 2011-05-31 | 2013-10-30 | 华南理工大学 | High-concentration pulp bleaching device |
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1996
- 1996-07-25 CN CN 96119117 patent/CN1050643C/en not_active Expired - Fee Related
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| CN1151460A (en) | 1997-06-11 |
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